A Hot-mold Ablation-cooling Method for Making Thin-walled Castings with Ductility Approaching Extrusions

A Hot-mold Ablation-cooling Method for Making Thin-walled Castings with Ductility Approaching Extrusions Qingyou Han1, Dongke Sun1, Xintao Liu1, Dashan Sui2, Jianhua Wu3 1School of Mechanical Engineering, Southeast University, Nanjing 211891, China 2School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200030, China 3Shandong Provincial Key Laboratory of High Strength Lightweight Metallic Materials, Advanced Materials Institute, Qilu University of Technology, Jinan 250014, China Abstract We have developed a casting process termed HMAC (hot mold ablation cooling) process that, for the first time, is capable of producing a large thin-walled casting of high integrity using only one feeder. The ductility of such a casting of A356 alloy was investigated. For comparison, conventional sand casting, permanent mold casting, and extrusions of the same size were made and their mechanical properties were measured. Experimental results indicated that the ductility of the castings made using the HMAC process was much higher than that using conventional casting processes, approaching that of extrusions. Such a high ductility of the castings made by this new process was due to the fact that shrinkage porosity was totally eliminated and the eutectic silicon was totally modified from flake-like to fine fibers owing to the water quench effect. Numerical simulation revealed that, at a given ablation velocity, the interdendritic feeding distance was reduced by increasing mold temperatures. T6 heat treatment could break up the silicon fibers into isolated particles at much shorter holding times during T4 stage. It is expected that the HMAC process could be capable of making complex components with properties approaching that of the forgings or extrusions. Such complex components are difficult to make using forging or extrusion processes. Keywords: Ablation cooling, mold heating, solidification, thin-walled casting, and mechanical properties. 1